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Slab Coil vs "A" Coil

What is the difference between a slab coil and an "A" coil of the same size/capacity and what the benefits of either?

We are in the process of replacing our upstairs AC with a new condenser and coil. Most installers have quoted A coils (which we have now), the last quoted Slab coils saying they were better, but not really giving me a reason.

A slab coil is just a flat coil. For the last 30-40 years or more they were the coil most often used when furnace was in horizontal position, A coils were used in the upflow or downflow position. Slabs require a duct transition to adapt to usually smaller furnace opening which is an extra expense to someone. In the last 10 years manufactures have adapted the A for use in the horizontal position. It does not require a duct transition. Coil style does not matter if the coil is matched to the condenser.

Slab coils give better airflow performance than A coils because the pressure drop through them is significantly lower.
My experience has been that they also tend to have fewer condensate disposal problems too.

Slab coils give better airflow performance than A coils because the pressure drop through them is significantly lower.
My experience has been that they also tend to have fewer condensate disposal problems too.

Yeah! They are easier to clean once you get through the transition too!

We frequently see slabs retrofitted to existing furnaces and supply air plenums with a large majority of the surface area on both the entering and exiting sides of the coil blocked off because no transition was used and existing supply air plenum is smaller than coil opening. Use an appropriate length transition, new supply air plenum, and if cleaning the the coil in the future is a concern have an access door installed in the transition.(an access door is not foil tape over the flap of sheetmetal cut out to look at coil)